Alkylbenzenes as diluents for elastomeric olefin polymers



30 Claims: c1. 260-33.6)

ABSTRACT OF THE DISCLOSURE Amorphous vulcanizable copolymers of ethylene and propylene or butene-l are extended by mixing the same with monoalkylbenzenes, polyalkylbenzenes, or mixtures thereof. The extenders comprise an aromatic nucleus having one or more linear or branched alkyl substituents containing from 1 to 20, preferably from 10 to 20, carbon atoms.

The present invention relates to vulcanizable compositions based on amorphous polymers of ethylene with an alpha-olefin containing as a plasticizer, extending or diluting agent, a monoor poly-alkylbenzene, and to the vulcanized articles obtained therefrom. More particularly, it relates to the dilution with monoor poly-alkylbenzenes of linear, amorphous, saturated copolymer of ethylene with propylene or butene-l, and to the vulcanized products thus obtained.

It is known that the aforementioned saturated copolymers having an elastomeric character, for their vulcanization require the addition of particularly reactive agents, such as organic peroxides, optionally accompanied by free-radical acceptors.

The technique of diluting the high molecular weight elastomers with parafiinic, naphthenic or aromatic lubrieating oils is also known. The products thus obtained (oil-extended rubbers) show the most varied characteristics.

For the unsaturated elastomers, the vulcanization product is not influenced, or only influenced to a minor extent, by the addition of either small, or even relatively large, amount of mineral oils.

On the other hand, in the case of saturated elastomers, such as the elastomeric copolymers of ethylene with alpha-olefins, which require, as said above, due to their structure, particularly reactive cross-linking agents, it is necessaryto use essentially paraffinic oils. In fact, peroxide vulcanization makes the use of naphthenic or aromatic oils, difficult, since they, by reacting with peroxide more easily than parafiinic oils due to the presence of more reactive positions in their structure, remarkably reduce the cross-linking power of the vulcanizing agents.

An object of the present invention is a vulcanizable composition based on saturated amorphous copolymers of ethylene with a higher alpha-olefin, such as propylene or butene-l, extended or plasticized with products which inter-react very little with the vulcanizing agents, remarkably less than the best parafiinic oils.

The ethylene-alpha-olefin copolymers preferably used according to the present invention are the ethylene-propylene or ethylene-butene-l copolymers having a molar ethylene content from 20 to 80% and a molecular weight between 50,000 and 800,000, preferably between 60,000 and 500,000.

The dilution according to the present invention consists of adding to a copolymer as defined above, and having a viscosity ML (1+4) 100 C. (ASTM D-1646-61) not lower than 20, and a molar ethylene content between -nited States Patent 20 and an alkyl benzene derivative in amount from 5 to 200 parts by weight per parts of polymer, in the presence of vulcanization agents, reinforcing fillers, and of other ingredients commonly used in the vulcanization industry.

The present invention thus relates to a vulcanizable composition based on amorphous copolymers'of ethylene with an alpha-olefin, containing a reinforcing filler, vulcanizing agents, an extending agent, possibly an antioxidant, characterized in that the extending agentis, selected from the group consisting of monoalkylbenzenes, polyalkylbenzenes and mixtures'thereof, consisting 'of an aromatic nucleus having one or more linear or branched alkyl substituents containing from 1 to 20 carbonatoms.

The alkylbenzenes can be easily obtained by Friedel- Crafts synthesis or by other common synthesis reactions.

The alkylbenzene dilution agents preferably have a viscosity varying from 2 to 100 centistokes at 100 C., a molecular weight comprised between 220 and 700 and should not contain moisture and various impurities; they must also have a good flow at low temperatures, a high flash point and boiling point, a low content of ashes and of total acidity.

For the alkylbenzenes according to the present invention, exemplary products are pure dodecylbenzene and the commercial product is Preadix 8. Preadix 8 is a mixture consisting of 50% of monoalkylbenzenes and 50% of polyalkylbenzenes in which the alkyl groups have a branched chain and contain about 15 carbon atoms.

Its appearance and physico-chemical characteristics are as follows: 1

Appearance Oily clear straw-yellow product.

Moisture and impurities Absent.

Specific gravity at 15 C 0.88.

Engler viscosity at 50 C. Viscosity in centistokes at 100 5.6

C. 7.1. Flash point (Penski-Martins) V Total a c i d i t y (neutralization Above 160 C.

number) 0.04%. Asphalt and resins Absent. Active sulfur Absent. Corrosion test on copper Negative. Ash Traces. Boiling point Above 300 C. Index of refraction (11 1.4899. Aniline point 69.5 C.

Another alkylbenzene that gives particularly good results is a mixture of decyl-, undecyl-, dodecyland tridecyl-benzene.

By using such akylbenzene products, mixes with a high diluent content and having physical characteristics of the vulcanizates higher than those normally obtained by using the best parafiinic oils were obtained.

The technique of addition of these diluents can be that usually adopted for the plasticizers, by operating in an open or inner mixer. The diluents can be added during the polymerization or in the successive stages. The fillers, other ingredients and the vulcanization agentsare then added to these mixtures of diluent and copolymer.

The reinforcing agent used can be of any type, more particularly of basic type, carbon black of any type, or a white mineral filler. The amount of reinforcingfiller to be used is between 10 and 200%, preferably'between 30 and by weight, referred to the copolymer.

The vulcanization agents to be used are organic peroxides, in amount from 0.1 to 10 parts by weight per 100 parts of copolymer. Any organic peroxide can be used; the most commonly used are dibenzoylperoxide,

dicumyl peroxide, tert.buty1peroxide, tert.butyl perbenzodiluent, carbon black and sulfur are prepared, while the ate and a,a'-bis(tert.butylperoxy)diisopropylbenzene, peroxide is added in an open mixer.

A free-radical acceptor in amount lower than the half The compositions of the mixes and the main mechanical by weight of the amount of peroxide may also be used. characteristics are reported in Table 1. As free-radical acceptor, sulfur, quinonic compounds, In the mixes containing the parafiinic oil, the forming furfural and its derivatives can be used. of the mix being the same, the interference of the oil with The vulcanization is carried out by heating the mixes the vulcanizing action of the peroxide is evident. Preadix to temperatures between 110 and 220 C., preferably be- 8, on the other hand, interferes to a minimum extent, and tween 140 and 180. C. makes it possible to obtain vulcanizates with remarkably The various commercial products used in the experibetter mechanical characteristics. ments are defined as follows: More precisely, by comparing the mechanical charac- TABLE 1 Trade Name Description Producer Circosol ZXH Naphthenic oil Sun Oil Co. Dutral N Ethylene-propylene copolymer with a Monteshell Petrochimrea S.p.A.

Mooney viscosity 351:5. Dutral Q Ethylene-propylene eopolymer with a Do.

Mooney viscosity 455:5. Dutral I Ethylene-propylene eopolymer with a Do.

Mooney viscosity above 50. Dutrex 68 Paraflinic oil Shell Oil Co.

1 d0 Montecatini S.p.A.

-- Polymerlzed 1, 2-dihydro-2,4,4-tri- Monsanto Chem. Co.

rnethylqulnollue. Para flinic o Hunfible Oil & Refining Co.

0 0. Paraflinie-naphthenic oil.. Esso Standard Italiana. Peroxlmon R40 u,n'Bis(tert.butyl peroxy) pro- Montecatini S.p.A.

us pylbenzene formulated at 40% with calcium carbonate. Preadix 8 Alkylbeuzene diluent 1.0.1.11. S.p.A. Torino (Italy).

Paraffinic oil Mobil Oil.

Aromatic oil.-- Sun Oil 00. Sun Process Aid 516 Paraffinie oil Do. Sun Process Aid 551. on Do.

The methods followed in the characterization tests of teristics of the vulcanizates in Tests A, B, C and D, with the vulcanizates were as follows: those of Tests E, F, G and H, respectively, in addition to the better cross-linking degree shown by the higher values Characteristics Breaking Reference of modulus at 300% of the vulcanizates of mixes contain- Ullit mg Preadix 8, also, lower values of permanent set, or a Tensile strength kg.lcm. ASTM-D-412. better elastic rebound as compared to the vulcanizates con- 'IIRHD nardr essl" k 'l gg g-g-ms B Furthermore, for example, from the comparison of ear strengt g. cm.. 624-5 type.

Tensile permanent set Percent--.. One hour under traction Tests 1E wlth D i i Observgd i 9.12 200% elongation at; approxima e y equa va ues 01. e on a 1011 at rea 3 11 fg fi g 1 of modulus, the vulcanizates of mixes E and F containing Mooney viscosity ASTM-1j-1646-61. Preadix 8 require only 4 and 6 parts respectively of Garvey extrudability index B.S. Garvey et a1. Ind.

vulcanizing agent whereas 8 and 10 parts respectively are Eng. Chem. 34,1309 (1942). See Example 3 5 required by the vulcanlzates of mixes C and D containing parafiinic oil.

TABLE 1.-EFFEOT OF THE DILUENT PREADIX 8 ON THE PEROXIDIG VULCANIZATION OF ETHYLENE-PROPYLENE COPOLYMER Tests .ABODEFGH Composition of the mixes:

Ethylene-propylene copolymer by 75 75 75 75 75 75 75 5305 of ethylene and ML(1+4) C.=

Oil FL-65 (paraifinie) 25 25 25 25 Diluent Preadix 8 25 25 25 25 Carbon black HAF 50 50 50 50 50 50 50 50 Sulfur 0. 3 0. 45 0. G 0. 75 0. 3 0. 45 0. G O. 75 Perox irnon F-4O 4 6 8 10 4 6 8 10 vulcanization conditions40 minutes at 0.

While the particular examples which follow are directed to comparison of alkylbenzene diluents with various paraf- EXAMPLE 2 .finic oils in regard to ethylene-propylene copolymers, re- Y Operating in an inner mixer, the mixes of P 'sults equally favorable to the use of alkylbenzene diluents diluent, Carbon black, antioxidant a d ulfur are prepared, can be obtained with regard to ethylene-butene-l copoly- 70 While the PBTOXidB is added in all p mixermers. The compositions of the mixes and the values of the The following examples serve to better ill t t th i main mechanical characteristics of the vulcanization are vention without limiting its scope. repo d in Table 2.

EXAMPLE I These mixes also contain an antioxidant. it is known t that most of the antioxidants used in the mixes of ethylene- By operating in an inner mixer, the mixes of polymer, propylene copolymers, such as Dutral, interfere with the peroxides during the vulcanization, thus causing a decrease of the main mechanical characteristics of the vulcanizate. Compare the mechanical characteristics of the vulcanizates of Table 2 with those of Table l, in which the same basic modes of operation were followed. If this effect is combined with the adverse affect of the oils, a worsening in the properties of the vulcanizates is obtained.

The results of Table 2, however, show that with Preadix 8 in the mix, it is still possible to obtain remarkably better results than with the vulcanizates containing parafiinic oil. By comparing e.g., Tests D and F, it is observed that the modulus being about the same, the vulcanizate containing Preadix 8 requires'only 6 parts of vulcanizing agent (peroximon F-40) against 10 parts consumed by the vulcanizate containing paraffinic oil. Moreover, from the comparison of Tests E and F of Table 2 with Tests B and C of Table 1, it also appears that, the modulus being about the same, the vulcanizates with Preadix 8, and protected by the antioxidant, Flectol H, require only 4 and 6 parts respectively of vulcanizing agent, instead of 6 and 8 parts respectively required by the vulcanizates containing paraflinic oil, and without antioxidant.

With the diluent Preadix 8, a remarkable economy in the use of peroxide is also obtained. For example, compare the higher modulus values in Tests E and F with the lower values in Tests A through D, in which as much and more peroxide was used than in Tests E and F.

The vulcanizates of ethylene-propylene copolymer, diluted with Preadix 8, as compared to the vulcanizates of mixes containing parafiinic oil Fl-65 (compare Tests A and B with E and F), with the same amount of crosslinking agent, show much better mechanical parameters. Compare, for instance, the higher tensile strength and modulus, and the lower elongation and permanent set. The values of these parameters are still satisfactorily compatible with the amounts of filler and diluent of the mixes. The vulcanizates containing paratfinic oil, on the other hand, are poor, and even with 9 parts of crosslinking agent, they do not reach the characteristics of the vulcanizates containing diluent Preadix 8 and only 5 parts of peroxide. Also, with the same cross-linking agent amount, the better elasticity (lower permanent set) of the vulcanizates containing Preadix 8 is further pointed out.

TRAL) IN THE PRESENCE OF ANTIOXIDANTS Tests A B C D E F G H Composition of the mixes:

Ethylene-propylene copolymer (50% by mole of ethylene and ML (14) 100 C. 10) 75 75 75 75 75 75 75 75 Oil FL-65 (p aratfinic) l l 25 25 25 25 Oil Preadix 25 25 25 25 Carbon black HAF... 50 50 50 50 50 50 50 50 Antioxidant Flectol H 0. 5 0. 5 0. 5 0. 5 0. 5 0. 5 g 0. 5 Zine oxide 5 5 5 5 5 5 5 Sulfur 0 3 0. 45 0. 6 0. 75 0. 3 0. 45 0.6 0.75 Peroximon F-40 4 6 8 4 6 8 10 vulcanization conditions-40 minutes at 165 0.

Characteristics of the vulcanizates:

Tensile strength, kgJcm. 162 157 157 146 172 164 160 150 Elongation at break, percent. 645 525 4-10 360 505 400 325 290 Modulus at 300%, kg./cm. 56 75 94 111 85 110 135 146 Permanent set at 200%, percent 10 8 7 7 8 6. 5 5 3. 5 Tear strength, kg./em 44 27 28 40 28 23 IRHD hardness 56. 5 58 61. 5 62. 5 58. 5 61. 5 .63 64. 5

EXAMPLE 3 In the current art, the Garvey die makes it possible I to extrude through a trapezoidal section, an extruded article which is evaluated on the basis of its section, top, surface and corners. To each parameter a score, from 1 to 4, 4 being very good, is given. The extrudability index is the sum of the four values given to each parameter. The maximum value is 16.

, In the case of extrudedarticles, very good values of the Garveys extrudability index of the mixes can be observed with Preadix 8, as compared to those with paraffinic oil. Compare Tests A and B with E and F.

TABLE 3 [The efiect of the diluent Preadix 8 in mixes of ethylene-propylene co trfllyrfiier (Dutral) suitable for low-hardness moulded or extruded ar 0 es Tests A B C D E F Composition of the mixes:

Ethylene-propylene copolymer 100 100 100 100 100 100 (50% by rnols of ethylene and. ML (1+4) 100 C.=).

Oil FL-65 (parafiinie) 50 50 50 Dlluent Preadix 8 50 50 FEB carbon black. 0 70 60 70 Sulfur 0.35 0.35 0. 5 0.7 0.35 0.35

Peroximon F-40 5 5 7 9 5 5 vulcanization conditions- 40 minutes at 165 C.

Characteristics of the vulcanizates:

Tensile strength, kg./c1n 62 67 91 92 99 Elongation at break, percent. 955 865 770 700 560 570 Modulus at 300%, kgJem. 16 20 31' 37 43 46' Permanent set at 200%, percent 21 20 l2 l0 8 7 Tear strength, kgJcm 33 41 42 40 28 37 IRHD hardness 32 36. 5 40 44 36 39 Garvey extrudability index of 14. 5 14 14 14 16 16 the crude mix.

7 EXAMPLE 4 By operating in an inner mixer, the mixes of polymer, diluent, carbon black and sulfur are prepared, while the peroxide is added in an open mixer. The compositions of the mixes and the values of the main mechanical characteristics of the vulcanizates are reported in Table 4.

These tests confirm the better behavior of Preadix 8, as compared to the paraiiinic oil used for comparison; It is seen that it is possible to obtain vulcanizates for lowhardness, moulded or extruded articles, containing large amounts of diluent and carbon black, and having good mechanical properties.

TABLE 4 [Efiect of the diluent Preadix 8 in the mixes of ethylene-propylene copolymer (Dutral) suitable for economical low-hardness moulded or extruded articles] Tests A B C D Composition of the mixes:

Ethylene-propylene copolymcr (50% by 100 100 100 100 mols4o)f ethylene and ML (1+4) 100 C.= 5 Oil FL-65 100 100 Diluent Preadix 8 100 100 FEF carbon black- 150 100 150 100 SRF carbon black 90 90 Sulfur 0.75 0.75 0. 75 0. 75 Peroximon F-40 10 10 10 10 Mooney viscosity of the mix 18. 5 22. 5 22 vulcanization conditions- 40 minutes at 165 0.

Characteristics of the vulcanizates:

Preadix 8, pure dodecyl benzene, and a mixture of decylundecyl-dodecyl-tridecylbenzenes (called mix AB), prepared in a laboratory by Friedel-Crafts synthesis, are exemplified. The mixture AB was found to have a specific gravity of 0.855 at 15 C., an index of refraction (n of 1.482 and a boiling point of 297-341 C.

TABLE 5 [Effect of various alkylbenzenes on the peroxidic vulcanization or ethylene-propylene copolymer (Dutral)] minutes at 160 0.

Characteristics of the vulcanizates:

Tensile strength, kg./cm. 174 166 160 153 Elongation at break, percent 405 320 420 320 Modulus at 300%, kg./cm. 99 153 112 141 Permanent set at 200%, percent- 6 5 6 4 IRHD hardness 64 58 57 64 EXAMPLE 6 By operating in an open mixer the mixes whose compositions are reported in Table 6 are prepared. In Table 6, it is shown that with the diluent Preadix 8 it is possible to obtain very good mechanical properties of the vulcanizates in comparison with various commercial parafiinic oils. Note, for instance, the high modulus and low permanent set obtained with Preadix 8.

TABLE 6.EFFECT OF THE DILUENT PREADIX 8 ON THE VULCANIZA- TION OF ETHYLENE-PROPYLENE COPOLYMER IN COMPARISON WITH COMMERCIAL PARAFFINIC OILS Tests ABCDEFGHI Composition of the mixes:

Ethylene-propylene copolymer by mols oi ethylene and ML (1+4) 100 C.=10). Diluent Preadix 8-. Oil FL-65 Sulfur Peroximon F-4 vulcanization conditions-40 minutes at 165 C Characteristics of the vnlcanizates:

Tensile strength, lag/c111. 173 107 158 169 165 108 156 Elongation at break, percent 385 590 580 580 600 585 605 600 620 Modulus at 300%, k n/cm). 116 64 68 69 59 G7 60 63 59 Permanent set at 200%, percent 4. 5 8 8 8 8.5 8 8. 5 8 0 IRHD hardness 58. 5 55 57 54 54 56 55. 5 56 57 EXAMPLE 5 As will be apparent, various changes in details may be By operating in an open mixer, thet mixes are prepared 70 made in the practice of this invention without departing whose compositions are reported in Table 5. In Table 5 are also reported the values of the main mechanical characteristics of the vulcanizates. They show that it is possible to obtain vulcanizates having good mechanical propfrom the spirit thereof. It is intended, therefore, to include in the scope of the appended claims, all such modifications in details as will be obvious to those skilled in the art from the description and working examples given erties by using various types of alkylbenzenes. Besides 75 herein.

What is claimed is:

1. A vulcanizable composition of saturated, amorphous copolymers of ethylene with a higher alpha-olefin selected from the group consisting of propylene and butene-l, and an extending agent selected from the group consisting of monoalkylbenzenes, polyalkylbenzenes and mixtures thereof, said benzenes having an aromatic nucleus with at least one alkyl substituent containing from 10 to carbon atoms.

2. A composition according to claim 1, in which the alkyl substituent is linear.

3. A composition according to claim 1, in which the alkyl substituent is branched.

4. A composition according to claim 1, in which the alkylbenzene extending agent has a viscosity of from 2 to 100 centistokes at 100 C., a molecular weight between about 420 and 700, is free from moisture and impurities, has a high flash point and boiling point, a low content of ash, a low total acidity, and has good flow at low temperatures.

5. A composition according to claim 1, in which the alkylbenzene extending agent is a mixture of alkylbenzones, in which the alkyl substituent of the various members of the mixture varies from 10 to 20 carbon atoms.

6. A composition according to claim 1, in which the alykylbenzene compound is pure dodecyl benzene.

7. A composition according to claim 1, in which the extending agent is a mixture of about of monoalkylbenzenes and about 50% of polyalkylbenzenes in which the alkyl groups have a branched chain and contain about 15 carbon atoms.

8. A composition according to claim 1, in which the extending agent is used in amount from 5 to 200 parts by weight per 100 parts of polymer.

9. A composition according to claim 1, in which the higher alpha-olefin is propylene.

10. A composition according to claim 1, in which the higher alpha-olefin is butene-l.

11. A composition according to claim 1, in which the ethylene content is from 20 to 12. A composition according to claim 1, in which the copolymer has a molecular weight of from 50,000 to 800,000.

13. A composition according to claim 12, in which the copolymer has a molecular weight of from 60,000 to 500,000.

14. A composition according to claim 9, in which the viscosity of the polymer, as determined according to ASTM D-1646-61, is at least 20.

15. A composition according to claim 1, which also contains a reinforcing filler and a vulcanization agent.

16. A composition according to claim 15, which also contains an antioxidant.

17. A composition according to claim 15, in which an organic peroxide in amount from 0.1 to 10 parts by Weight per parts of copolymer is used as vulcan'izing agent.

13. A composition according to claim 17, in which a free-radical acceptor in amount lower than half by weight of the peroxide amount is used.

19. A composition according to claim 18, in which the free-radical acceptor is selected from the group consisting of sulfur, quinonic compounds, furfural and its derivatives.

20. A composition according to claim 15, in which the reinforcing filler is carbon black.

21. A composition according to claim 15, in which the reinforcing filler is used in an amount between 10 and 200% by weight of the copolymer.

22. A process for preparing vulcanizates having high mechanical properties comprising preparing a vulcanizable composition containing a saturated amorphous copolymer of ethylene and a higher alpha-olefin selected from the group consisting of propylene and butene-l, a reinforcing filler, a vulcanizing agent and an extending agent for the copolymer selected from the group consisting of monoalkylbenzenes, polyalkylbenzenes and mixtures thereof, said benzenes having an aromatic nucleus and at least one alkyl substituent containing 10 to 20 carbon atoms, and then vulcanizing this mixture at a temperature between and 220 C.

23. A process according to claim 22, in which the temperature is between and 180 C.

24. A process according to claim 22, in which said composition contains 5 to 200 parts by weight of extending agent per 100 parts of polymer.

25. A process according to claim 22, in which the higher alpha-olefin is propylene.

26. The process according to claim 22, in which the higher alpha-olefin is butene-l.

27. A process according to claim 22, in which the vulcanizable composition also contains an antioxidant.

28. A process according to claim 22, for preparing low hardness articles, in which, in the vulcanizable composition, an amount of extending .agent of at least 1 part for every 2 parts by weight of polymer is used, and in which an amount of filler of at least 6 parts for every 10 parts by weight of polymer is used.

29. A process according to claim 22, in which economical, low hardness articles are produced in which the amount of extending agent used is at least one part per part by weight of polymer, and in which the amount of filler is at least one part of filler per part by weight of polymer.

30. Vulcanized elastomers obtained according to the process of claim 22.

References Cited UNITED STATES PATENTS 5/1959 Darby. 1/ 1967 Portolani et a1. 26041 

